There have been developed closures for containers, particularly cans, which include removable end panels. These closures include a peripheral frame having peelably bonded thereto an end panel. When containers incorporating such closures are subjected to post-filling treatment including retorting or high vacuum, positive or negative pressure is built up within the container with the result that the end panel flexes axially outwardly or inwardly and has a tendency to internally initiate peeling from the frame. This can result in improperly sealed containers.
Another problem with closures of this type is the securement of the closure to the container. There is a great need for a closure which can be tightly sealed and permanently attached to a container by merely applying heat and an axial pressure on the closure after it has been seated on the container.